This invention relates to a catheter introducer assembly for infusing a desired medication into the body of a patient. More particularly, this invention relates to such a catheter intoducer assembly wherein the introducer is a thin-walled but comparatively rigid tubular structure for receiving through the lumen thereof a catheter. The catheter, as a result of the support of the introducer, is of very flexible soft material. Both the catheter and the introducer are comprised of a material, such as a polyurethane, which softens and swells during exposure to body fluids. The material may be hydrophilic. As a result, the assembly, when introduced through the skin of a patient, and when exposed to body fluids, both the introducer and the catheter soften to alleviate any trauma and/or pain to the patient during insertion and subsequent infusion.
More particularly, the introducer is considerably shorter than the catheter so that the front end of the catheter extends outwardly from the front end of the introducer. The catheter includes, in the part which extends from the front end of the introducer, a plurality of openings for infusing liquids into the patient. These openings are of a dimension which allows infusion of liquids under pressure, but which prevents return flow of blood. Therefore, the assembly may be inserted through the skin of a patient and into place for infusion, but liquid infusion may be intermittent without any return blood flow when infusion is not taking place.
The dimensions of the fluid infusion holes through the walls of the front end of the catheter is within the range of between about 0.0005 and 0.005 inches. This allows for discontinuous fluid injection without any return flow. Moreover, the distal or front end of the catheter is rounded to reduce trauma during insertion. Thus, with the combination of the very thin-walled very soft introducer which softens and swells upon exposure to body fluids, and the catheter distal end being comprised of an even thinner-walled material because it is supported by the introducer, and with the front end of the catheter being rounded or having a blunt end, there is a substantial reduction in trauma and/or discomfort to a patient during insertion and during the time when the assembly remains inserted in the patient.
The catheter, moreover, contains an additive so that the infusion holes may be drilled with a laser in a material having sufficient laser absorption characteristics to vaporize under the effect of a laser beam. For more detail involving this procedure, reference is made to U.S. application Ser. No. 350,960, filed, May 11, 1989, which is hereby incorporated by reference in its entirety.
In the past, arrangements have been provided for preventing backflow of body fluids in a catheter assembly. Representative of such structures is taught in U.S. Pat. No. 4,883,461 in which an assembly, with a deliberate return valve, is constructed to prevent backflow. However, the assembly depends upon the movement of the valve and under blood coagulating conditions, this may fail on certain occasions. At any rate, the actual structure described and claimed in U.S. Pat. No. 4,883,461 is arranged to allow body fluid flow for withdrawing body fluids from a patient.
A further patent with an insertion catheter device is that of U.S. Pat. No. 5,009,636 wherein a dual lumen catheter apparatus is provided with multiple openings in the distal end thereof. However, this device is specifically arranged to have openings which receive body fluid for withdrawing from the body as well as inserting body fluid into the body to provide a circulation feature for treating blood and returning it to the body. U.S. Pat. No. 4,976,697 teaches an assembly for allowing insertion of a catheter into the body and allowing placement for intermittent administration of fluids to the patient. In that structure, an obturator assembly is provided for deliberately occluding the catheter when administration is not taking place. The arrangement includes a feed structure for allowing intermittent opening and occlusion of the lumen of the catheter which remains in place.
Finally, U.S. Pat. No. 4,648,519 teaches a plurality of openings in the cap of a container for allowing gas flow through the cap without allowing any liquid flow through the cap. However, this device does not teach or recognize the intermittent introduction of fluids under pressure through orifices of the kind discussed here, while preventing the undesirable flow of blood in the return direction.
With this invention, by contrast, and as noted above, a catheter introducer assembly is provided which utilizes extremely thin-walled structures in the form of an introducer, and a catheter with a blunt nosed distal end, which catheter and introducer both soften upon contact with body fluids for reducing trauma when introduced into the body of a patient for the infusion of fluids. Nevertheless, the assembly, because of its softening nature and thin walls may remain in place without undue trauma to the patient for intermittent infusion of fluids without any return flow of blood or other body fluids from the body through the assembly.
Moreover, because the assembly prevents backflow, expensive heparin and/or saline locks are obviated. The actual polymers comprising the two parts of the assembly herein may have incorporated therein anti-infective ingredients and/or lubricants which have the effect of reducing infection during the in-place positioning of the assembly of the invention, as well as reducing further trauma during insertion.
Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings and the appended claims.